High-pressure fuel pumps in fuel injection systems are used for applying a high pressure to a fuel, wherein for example in the case of gasoline internal combustion engines the pressure lies in a range from 150 bar to 500 bar and in the case of diesel internal combustion engines the pressure lies in a range from 1500 bar to 3000 bar. The higher the pressure that can be generated in the respective fuel, the lower the emissions that are produced during the combustion of the fuel in a combustion chamber, which, in particular against the background that the reduction of emissions is becoming increasingly desirable, is advantageous.
The fuel is in this case compressed in the high-pressure fuel pump in a pressure chamber provided for this and is then usually fed by way of a high-pressure connection to a pressure accumulator arranged hydraulically downstream of the pressure chamber, known as the common rail, from where the fuel can then be injected by way of injectors into combustion spaces of the combustion chambers. The fuel injection system is a hydraulic system, in which passive valves such as for example check valves are used at various points in order only to allow the pressurized fuel to be passed on as from a predefined pressure level. Such check valves may comprise outlet valves in the high-pressure connection of the high-pressure fuel pump, but also as pressure limiting valves, which in the event of overpressure divert excess fuel away from the high-pressure region of the fuel injection system in order to relieve it.
Check valves for such applications that are known from the prior art, for example from DE 10 2014 206 968 A1, are normally made up of three main components, specifically a sealing element, a coil spring, which preloads the sealing element onto an associated valve seat, and a valve securing element, on which the helical spring is supported. This spring securing element is normally pressed into a corresponding hole, through which the fuel under high pressure is intended to be passed on.
It is however becoming increasingly more difficult to ensure a reliable interference fit between this spring securing element and a high-pressure component in which this hole has been made if the pressures reside in a range of greater than 2000 bar. This is so because, as a consequence of the internal pressure, the high-pressure component expands in the region of the hole, wherein this expansion removes the tensioning from the interference-fit assembly and the spring securing element begins to move around in the hole in which it is held. Then the check valve no longer functions as a valve. In addition, the spring securing element as a component itself may require an additional installation space within the high-pressure component in which it is accommodated.